// author: Rachel Gollub, 1995

// Bubbles!

import java.awt.Color;
import java.awt.Graphics;

public class Bubbles extends java.applet.Applet implements Runnable {
	Thread artist = null;
	int bubble = 0, thisbubble = 0; // # of bubbles on screen, and current
	// bubble
	int MAXBUBBLES = 25; // Maximum bubbles on screen
	int stepper = 4; // Counter for which bubbles to move when
	int record[][] = new int[MAXBUBBLES][5]; // Array that holds bubbles

	public void init() {
		resize(300, 100); // Set bubble window size
	}

	public void draw_bubble(int x, int y, int r, Color col, Graphics g) {
		int i;
		for (i = x - r; i <= x + r; i++) { // Draws a circle
			g.setColor(col);
			g.drawLine(i, y - (int) (Math.sqrt(r * r - ((i - x) * (i - x)))),
					i, y + (int) (Math.sqrt(r * r - ((i - x) * (i - x)))));
		}
	}

	public void move_bubble(int x, int y, int r, Color col, int step, Graphics g) {
		int i;
		for (i = x - r; i <= x + r; i++) { // Draws the upper edge of a circle
			g.setColor(col);
			g.drawLine(i, y - (int) (Math.sqrt(r * r - ((i - x) * (i - x)))),
					i, y + step
							- (int) (Math.sqrt(r * r - ((i - x) * (i - x)))));
		}
		for (i = x - r; i <= x + r; i++) { // Draws the lower edge of the
			// circle
			g.setColor(Color.white);
			g.drawLine(i, y + (int) (Math.sqrt(r * r - ((i - x) * (i - x)))),
					i, y + step
							+ (int) (Math.sqrt(r * r - ((i - x) * (i - x)))));
		}
	}

	public void paint(Graphics g) {
		int i, j, tmp;
		if (bubble < MAXBUBBLES || thisbubble < MAXBUBBLES) {
			record[thisbubble][0] = (int) (Math.random() * 500);
			record[thisbubble][1] = 550;
			record[thisbubble][2] = (int) (Math.random() * 500) / 20;
			record[thisbubble][3] = (int) (Math.random() * 255);
			record[thisbubble][4] = (int) (Math.random() * 255);
			draw_bubble(record[thisbubble][0], record[thisbubble][1],
					record[thisbubble][2], new java.awt.Color(
							record[thisbubble][3], record[thisbubble][4], 255),
					g);
			if (bubble < MAXBUBBLES) {
				bubble++;
				thisbubble++;
			} else
				thisbubble = MAXBUBBLES;
		}
		for (i = 0; i < bubble; i++) {
			if (i % 5 <= stepper) { // Steps each bubble at a different speed
				record[i][1] -= 1;
				move_bubble(record[i][0], record[i][1], record[i][2],
						new java.awt.Color(record[i][3], record[i][4], 255), 1,
						g);
				for (j = 0; j < i; j++) { // Checks for touching bubbles, pops
					// one
					tmp = ((record[i][1] - record[j][1])
							* (record[i][1] - record[j][1]) + (record[i][0] - record[j][0])
							* (record[i][0] - record[j][0]));
					if (j != i && Math.sqrt(tmp) < record[i][2] + record[j][2]) {
						for (tmp = record[i][2]; tmp >= -1; tmp = tmp - 2)
							draw_bubble(record[i][0], record[i][1],
									record[i][2] - tmp, Color.white, g);
						draw_bubble(record[j][0], record[j][1], record[j][2],
								new java.awt.Color(record[j][3], record[j][4],
										255), g);
						record[i][1] = -1;
						record[i][2] = 0;
					}
				}
			}
			if (record[i][1] + record[i][2] < 0 && bubble >= MAXBUBBLES) {
				thisbubble = i;
			}
			stepper = (int) (Math.random() * 10);
		}
	}

	public void update(Graphics g) {
		paint(g);
	}

	public void start() {
		if (artist == null) {
			artist = new Thread(this);
			artist.start();
		}
	}

	public void stop() {
		artist = null;
	}

	public void run() {
		while (artist != null) {
			try {
				Thread.sleep(100);
			} catch (InterruptedException e) {
			}
			repaint();
		}
		artist = null;
	}
}